The overall goal of the project is to better understand the transport properties of the skin and the phenomenon of percutaneous absorption. Our proposed work for the 09/01/75 - 08/31/76 period includes: (1) The measurement of the sorption of various compounds by the lipids of the stratum corneum. This study involves the extraction of stratum corneum lipids, their separation into major classes by chromatography and finally the measurement of the uptake of selected compounds by these lipids from aqueous solution. (2) The measurement of the skin penetration rates (in vitro) of high molecular weight alcohols by the solvent-deposition method. (3) Continued theoretical work on a model for percutaneous absorption emphasizing particularly the effect of hydration on the diffusion coefficient. (4) Measurement of the apparent adjuvant effect of propanol-water solutions on skin penetration. BIBLIOGRAPHIC REFERENCES: Scheuplein, R. J.: Permeability of the Skin, Handbook of Physiology. Section on Environmental Physiology. In press, 1975. Scheuplein, R.J. and King, P.N.: Solubility of Organic Molecules in the Lipids of the Stratum Corneum. Presented at the Society for Investigative Dermatology, May, 1975.